Arjia City was regarded as the spiritual center of the Grid. It was home to both Basics and ISOs, known collectively as Arjians. It was created in TC146 by an Alpha-class ISO named Jalen to house a growing number of devotees to purported oracle Radia. Arjia is strategically located directly over the codestream nexus.

Arjia was the site of the largest attack on ISO-friendly locations by Clu and his forces during the Purge, eventually leading to the city's destruction.

Well-known locations within Arjia included the Hub and Codestream Nexus.